Currently, LIN protocol is one of main protocols applied to a car, an LIN employing the LIN protocol includes a master node and multiple slave nodes, and the number of the slave nodes is no more than 15. The slave nodes may be used as a detector component (i.e. sensor) or an execution component (i.e. actuator), such as various types of detection modules and electric motor driver modules within the car. Due to the large number of the slave nodes, low power consumption of each slave node is beneficial to reduce power consumption of the whole LIN.
In addition, for the slave nodes applied to a car, it is also demanded that the power consumption of the slave nodes is as low as possible in the applied environment, particularly in a high temperature environment within an engine compartment, the temperature of the environment under which the engine successively can be up to 125 degree centigrade. Under such the high temperature environment, even an extra power is increased slightly, the temperature of the modules is raised greatly, and the reliability of the modules is reduced, as a result, a higher-level device can be employed only, which increases production cost.
A slave node applied to an LIN bus is disclosed in U.S. Pat. No. 7,701,943. With reference to FIG. 1, the slave node disables an LIN transmitting module 66 when receiving a signal, and activates the LIN transmitting module 66 only when transmitting an LIN signal, in this way, power consumption is reduced. In a case that the technical solution described in the patent is applied in an executor which is not required to operate successively, such as the slave node shown in U.S. Pat. No. 7,701,943, a defect of the invention of the patent is apparent. In such an application, the executor switches to a sleep state after completing a task, that is, a processor 62 (PROCESSING DEVICE) and an executing unit (HVAC LOUVRE MOTOR UNIT) shown in the FIG. 1 are also disabled or hibernated, to realize power saving. Generally, a period within which the executor is in the sleep state is much more than a period within which the executor executes the task, these modules or components cannot be disabled or herniated during the period within which the executor is in the sleep state, extra power consumption is generated. Also, the longer time the executor is in the sleep state, the larger the unnecessary extra power consumption is, and the more apparent the imperfection of the invention is.
For example, an average current is 100 mA in a case that a controlled component is driven to operate by the executor, and an average current is 10 mA in a case that the controlled component does not operate and all modules are maintained to be in an activated state, where the current greater than 8 mA is generated by the processing module and the driver module. Specifically, in a case that the period within which the executor does not operate is above 12.5 times longer than the period within which the executor operates, the extra power consumption is greater than actual effective power consumption. Generally, the ratio may be higher, which results in that the extra power consumption is much greater than the actual effective power consumption.
There are various types of slave nodes in an LIN. Some nodes can be switched to the sleep state in a case that the bus in the hibernated state, and some nodes can partially be switched to the sleep state even in a case that the bus is awake. In a case that the solution described above is applied to all slave nodes within the network, large extra power consumption is generated. The more the slave nodes are, the larger the LIN is, and the greater the defect is. In the solution described in the patent, the LIN transmitting module is activated only when required to transmit the LIN signal, in this way, the power consumption of the whole slave node may be reduced partially, however, the effect is not significant. With reference to FIG. 1, it can be seen that, besides an LIN receiving module 60 and the LIN transmitting module 66, the node includes a processing module 62 and an IGFS sensor module 64, extra power consumption is also generated in a case that the processing module 62 and the IGFS sensor module 64 are maintained to be in the activated state when these modules are not required to operate. The LIN transmitting module only performs a logical level conversion function, the processing module 62 is a control center of the whole node, and the sensor module 64 is a function executing component, compared with the LIN transmitting module, the processing module 62 and the sensor module 64 have more complex function and larger power consumption, the invention described above does not relates to how to reduce power consumption of the module within the node having the largest power consumption, which is to be improved by the disclosure.